GRANVILLE, Ohio -- A Cathedral Preparatory School graduate from Erie, who attended Denison University, was found dead Saturday night after he'd been missing for more than 20 hours.

David M. Hallman III was discovered Saturday at about 10:30 p.m. by university staff members who had joined a search for the student, Granville, Ohio, police said. Police said Hallman was last seen Saturday at 2 a.m. leaving Brews Cafe, a bar and restaurant in Granville, which is about 35 miles northeast of Columbus.

Police said the cause of Hallman's death was unknown and under investigation and alcohol was suspected of being a factor in the case. He was found in regular clothing, without a heavy coat, and possibly suffered from exposure, police said.

A statement released by Denison University on Sunday said it appeared Hallman "had fallen asleep and then succumbed to hypothermia."

Hallman, 21, was the son of David and Andrea Hallman and had been on the swimming teams at Denison and Prep, from which he graduated in 2010.

"We're all in shock," said the Rev. Scott Jabo, president of Erie Catholic Preparatory School, which includes Cathedral Prep and Villa Maria Academy.

Jabo said Hallman has a sister at Villa and counselors would be available today at both schools for students who knew him.

Besides being on the high school's swim team, Jabo said, Hallman had been "well-liked" and was an "excellent student."

Jabo said the school community extended its sympathy to the Hallman family, which he said was in Ohio on Sunday.

"We are prayerfully supporting them," he said.

Police said it was Hallman's father who reported him missing Saturday a little before 1 p.m. after he missed a noon appointment and couldn't be reached by cell phone.

Searches were conducted throughout Saturday on the ground and by air and using a K-9 unit, police said. Hallman's car was found on the university campus, police said.

His body was found in front of a residential garage about half a mile from where he was last seen, police said.

University officials said Sunday that counselors and clergy had been called to the campus to help people cope with his death.

"David was a wonderful young man who was widely admired by our campus community," said Denison University President Adam Weinberg as part of the university's statement. "Right now our focus is on supporting our students."

DANA MASSING can be reached at 870-1729 or by e-mail. Follow her on Twitter at twitter.com/ETNmassing.